I would like to think that some local commander would view any order to do so an illegal and quietly get them out of that country and once in America the vast majority of general public would not allow them to be returned. Baring that I could see some of their fellow soldiers 'refusing' to let them be handed over. This would all be a last resort, but they would act knowing that if they fail to do so their fellow soldiers would be killed for political considerations.

It would cost them their careers, maybe their freedom. But I cannot see them standing by and let their fellow soldiers be led to slaughter.

I cannot think of a sane reason of why they would do it, several insane reasons come to mind, white guilt, hate America, plain stupidity, plain spite. Any sane, honest person would have to realise that in the long run it's all going to get ugly, so why start it in the first place.